Method for transmitting an uplink signal in a wireless communication system, and apparatus for same

ABSTRACT

A method of transmitting a sounding reference signal (SRS) by a user equipment in a wireless communication system, a non-transitory computer readable medium on which a program for executing the method is recorded, and a user equipment for performing the method are discussed. The method according to one embodiment includes receiving a physical downlink control channel (PDCCH) including a carrier indicator field (CIF) and an SRS field via a first component carrier (CC) among a plurality of CCs including the first CC and one or more second CCs, the CIF indicating a specific CC and the SRS field indicating whether the user equipment has to transmit the SRS; transmitting the SRS on an uplink subframe; and receiving a first medium access control (MAC) information. If a bit for the specific CC in a bitmap has been disabled, the specific CC and SRS transmission on the specific CC are deactivated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending U.S. application Ser.No. 14/521,205 filed on Oct. 22, 2014, which is a continuation of U.S.application Ser. No. 13/577,830 filed on Aug. 8, 2012, now U.S. Pat. No.8,885,589, which is the National Phase of PCTKR2011/000070 filed on Jan.6, 2011, which claims the benefit under 35 U.S.C. §119(e) to U.S.Provisional Application No. 61/302,940, filed on Feb. 9, 2010. Thecontents of all of these applications are hereby incorporated byreference as fully set forth herein in their entirety.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to a wireless communication system, andmore particularly, to a method and apparatus for transmitting an uplinksignal in a wireless communication system.

2. Discussion of the Background Art

As an example of a mobile communication system to which the presentinvention is applicable, a 3^(rd) Generation Partnership Project (3GPP)Long Term Evolution (LTE) communication system will be schematicallydescribed.

FIG. 1 is a diagram showing a network structure of an Evolved UniversalMobile Telecommunications System (E-UMTS) as a mobile communicationsystem. The E-UMTS is an evolved form of the UMTS and has beenstandardized in the 3GPP. Generally, the E-UMTS may be called a LongTerm Evolution (LTE) system. For details of the technical specificationsof the UMTS and E-LIMTS, refer to Release 7 and Release 8 of “3^(rd)Generation Partnership Project; Technical Specification Group RadioAccess Network”.

Referring to FIG. 1, the E-UMTS mainly includes a User Equipment (UE)120, base stations (or eNBs or eNode Bs) 110 a and 110 b, and an AccessGateway (AG) which is located at an end of a network (E-UTRAN) and whichis connected to an external network. Generally, an eNB cansimultaneously transmit multiple data streams for a broadcast service, amulticast service and/or a unicast service.

One or more cells may exist per eNB. The cell is set to use a bandwidthsuch as 1.25, 2.5, 5, 10, 15 or 20 MHz to provide a downlink or uplinktransmission service to several UEs. Different cells may be set toprovide different bandwidths. The eNB controls data transmission orreception of a plurality of UEs. The eNB transmits downlink (DL)scheduling information of DL data so as to inform a corresponding UE oftime/frequency domain in which data is transmitted, coding, data size,and Hybrid Automatic Repeat and reQest (HARQ)-related information. Inaddition, the eNB transmits uplink (UL) information of UL data to acorresponding UE so as to inform the UE of a time/frequency domain whichmay be used by the UE, coding, data size and HARQ-related information.An interface for transmitting user traffic or control traffic can beused between eNBs. A Core Network (CN) may include the AG and a networknode or the like for user registration of the UE. The AG managesmobility of a UE on a Tracking Area (TA) basis. One TA includes aplurality of cells.

Although wireless communication technology has been developed up to LongTerm Evolution (LTE) based on Wideband Code Division Multiple Access(WCDMA), the demands and the expectations of users and providerscontinue to increase. In addition, since other radio access technologieshave been continuously developed, new technology evolution is requiredto secure high competitiveness in the future. Decrease in cost per bit,increase in service availability, flexible use of a frequency band,simple structure, open interface, suitable User Equipment (UE) powerconsumption and the like are required.

Recently, the standardization of the subsequent technology of the LTE isongoing in the 3GPP. In the present specification, the above-describedtechnology is called “LTE-Advanced” or “LTE-A”. The LTE system and theLTE-A system are different from each other in terms of system bandwidth.The LTE-A system aims to support a wideband of a maximum of 100 MHz. Thesystem uses carrier aggregation or bandwidth aggregation technologywhich achieves the wideband using a plurality of frequency blocks. Thecarrier aggregation enables the plurality of frequency blocks to be usedas one large logical frequency band in order to use a wider frequencyband. The bandwidth of each of the frequency blocks may be defined basedon the bandwidth of a system block used in the LTE system. Eachfrequency block is transmitted using a component carrier.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method and apparatusfor transmitting an uplink signal in a wireless communication system.

The technical problems solved by the present invention are not limitedto the above technical problems and other technical problems which arenot described herein will become apparent to those skilled in the artfrom the following description.

The object of the present invention can be achieved by providing amethod of transmitting an uplink data signal by a user equipment in awireless communication system including receiving control informationfor transmitting the uplink data signal in a specific subframe from abase station, allocating resources for the uplink data signal accordingto the control information, and transmitting the uplink data signalusing the allocated resources, wherein the control information includesresource extension information indicating whether a last symbol of thespecific subframe is allocated as resources for transmitting the uplinkdata.

In another aspect of the present invention, there is provided a userequipment (UE) of a wireless communication system including a receptionmodule configured to receive control information for transmitting anuplink data signal in a specific subframe from a base station, aprocessor configured to allocate resources for the uplink data signalaccording to the control information, and a transmission moduleconfigured to transmit the uplink data signal using the allocatedresources, wherein the control information includes resource extensioninformation indicating whether a last symbol of the specific subframe isallocated as resources for transmitting the uplink data

The control information may include resource extension information forallocating the last symbol of the specific subframe as the resources fortransmitting the uplink data if a frequency band for transmitting theuplink data signal at the UE in the specific subframe does not overlap abandwidth for transmitting a sounding reference signal of other UE.

The control information may be received via a physical downlink controlchannel (PDCCH) or a physical downlink shared channel (PDSCH), theresource extension information may be 1-bit information included in thecontrol information, and the resource extension information may beexpressed by a scrambling sequence applied to the control information.

The sounding reference signal of the other UE may be an aperiodicsounding reference signal.

According to the embodiments of the present invention, it is possible toefficiently transmit an uplink signal at a user equipment (UE) in awireless communication system.

The effects of the present invention are not limited to theabove-described effects and other effects which are not described hereinwill become apparent to those skilled in the art from the followingdescription.

BRIEF DESCRIPTION OF DRAWING:

FIG. 1 is a diagram showing a network structure of an Evolved UniversalMobile Telecommunications System (E-UMTS) as an example of a wirelesscommunication system.

FIG. 2 is a diagram showing a control plane and a user plane of a radiointerface protocol architecture between a User Equipment (UE) and anEvolved Universal Terrestrial Radio Access Network (E-UTRAN) based on a3^(rd) Generation Partnership Project (3GPP) radio access networkstandard.

FIG. 3 is a diagram showing physical channels used in a 3GPP system anda general signal transmission method using the same.

FIG. 4 is a diagram showing the structure of a radio frame used in aLong Term Evolution (LTE) system.

FIG. 5 is a diagram showing the functional structure of a downlink radioframe in an LTE system.

FIG. 6 is a diagram showing a control channel included in a controlregion of a subframe in an LTE system.

FIG. 7 is a diagram showing the structure of an uplink subframe used inan LTE system.

FIG. 8 is another diagram showing the structure of an uplink subframe inan LTE system.

FIG. 9 is a conceptual diagram illustrating carrier aggregation.

FIG. 10 is a diagram showing the structure of DCI formats 3 and 3A in anLTE system.

FIG. 11 is a diagram illustrating a method of schedulingactivation/deactivation of a downlink component carrier according to anembodiment of the present invention.

FIG. 12 is a diagram illustrating a method of schedulingactivation/deactivation of sounding reference signal transmission of anuplink component carrier according to an embodiment of the presentinvention.

FIG. 13 is a diagram illustrating a method of simultaneously schedulingactivation/deactivation of a downlink component carrier andactivation/deactivation of sounding reference signal transmission of anuplink component carrier according to an embodiment of the presentinvention.

FIG. 14 is a block diagram showing a communication apparatus accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The configuration, operation and other features of the present inventionwill be understood by the embodiments of the present invention describedwith reference to the accompanying drawings. The following embodimentsare examples of applying the technical features of the present inventionto a 3^(rd) Generation Partnership Project (3GPP) system.

In the present specification, a 3G-PP LTE (Release-8) system is referredto as an LTE system or a legacy system. A UE supporting an LTE system isreferred to as an LTE UE or a legacy UE. A 3GPP LTE-A (Release-9) systemis referred to as an LTE-A system or an advanced system. A UE supportingan LTE-A system is referred to an LTE-A UE or an advanced UE.

Although, for convenience, the embodiments of the present invention aredescribed using the LTE system and the LTE-A system in the presentspecification, the embodiments of the present invention are applicableto any communication system corresponding to the above definition. Inaddition, although the embodiments of the present invention aredescribed based on a Frequency Division Duplex (FDD) scheme in thepresent specification, the embodiments of the present invention may beeasily modified and applied to a Half-Duplex FDD (H-FDD) scheme or aTime Division Duplex (TDD) scheme.

FIG. 2 shows a control plane and a user plane of a radio interfaceprotocol between a UE and an Evolved Universal Terrestrial Radio AccessNetwork (E-UTRAN) based on a 3GPP radio access network standard. Thecontrol plane refers to a path used for transmitting control messagesused for managing a call between the UE and the network. The user planerefers to a path used for transmitting data generated in an applicationlayer, e.g., voice data or Internet packet data.

A physical (PHY) layer of a first layer provides an information transferservice to a higher layer using a physical channel. The PHY layer isconnected to a Medium Access Control (MAC) layer located on a higherlayer via a transport channel. Data is transported between the MAC layerand the PHY layer via the transport channel. Data is also transportedbetween a physical layer of a transmitting side and a physical layer ofa receiving side via a physical channel. The physical channel uses atime and a frequency as radio resources. More specifically, the physicalchannel is modulated using an Orthogonal Frequency Division MultipleAccess (OFDMA) scheme in downlink and is modulated using aSingle-Carrier Frequency Division Multiple Access (SC-FDMA) scheme inuplink.

A Medium Access Control (MAC) layer of a second layer provides a serviceto a Radio Link Control (RLC) layer of a higher layer via a logicalchannel. The RLC layer of the second layer supports reliable datatransmission. The function of the RLC layer may be implemented by afunctional block within the MAC. A Packet Data Convergence Protocol(PDCP) layer of the second layer performs a header compression functionto reduce unnecessary control information for efficient transmission ofan Internet Protocol (IP) packet such as an IPv4 packet or an IPv6packet in a radio interface having a relatively small bandwidth.

A Radio Resource Control (RRC) layer located at the bottom of a thirdlayer is defined only in the control plane and is responsible forcontrol of logical, transport, and physical channels in association withconfiguration, re-configuration, and release of Radio Bearers (RBs). TheRB is a service that the second layer provides for data communicationbetween the UE and the network. To accomplish this, the RRC layer of theUE and the RRC layer of the network exchange RRC messages. The UE is inan RRC connected mode if an RRC connection has been established betweenthe RRC layer of the radio network and the RRC layer of the UE.Otherwise, the UE is in an RRC idle mode. A Non-Access Stratum (NAS)layer located above the RRC layer performs functions such as sessionmanagement and mobility management.

One cell of the eNB is set to use a bandwidth such as 1.25, 2.5, 5, 10,15 or 20 MHz to provide a downlink or uplink transmission service toseveral UEs. Different cells may be set to provide different bandwidths.

Downlink transport channels for transmission of data from the network tothe UE include a Broadcast Channel (BCH) for transmission of systeminformation, a Paging Channel (PCH) for transmission of paging messages,and a downlink Shared Channel (SCH) for transmission of user traffic orcontrol messages. Traffic or control messages of a downlink multicast orbroadcast service may be transmitted through a downlink SCH and may alsobe transmitted through a downlink multicast channel (MCH). Uplinktransport channels for transmission of data from the UE to the networkinclude a Random Access Channel (RACH) for transmission of initialcontrol messages and an uplink SCH for transmission of user traffic orcontrol messages. Logical channels, which are located above thetransport channels and are mapped to the transport channels, include aBroadcast Control Channel (BCCH), a Paging Control Channel (PCCH), aCommon Control Channel (CCCH), a Multicast Control Channel (MCCH), and aMulticast Traffic Channel (MTCH).

FIG. 3 is a diagram showing physical channels used in a 3GPP system anda general signal transmission method using the same.

A UE performs an initial cell search operation such as synchronizationwith an eNB when power is turned on or the UE enters a new cell (S301).The UE may receive a Primary Synchronization Channel (P-SCH) and aSecondary Synchronization Channel (S-SCH) from the eNB, performsynchronization with the eNB, and acquire information such as a cell ID.Thereafter, the UE may receive a physical broadcast channel from the eNBso as to acquire broadcast information within the cell. Meanwhile, theUE may receive a Downlink Reference Signal (DL RS) so as to confirm adownlink channel state in the initial cell search step.

The UE which completes the initial cell search may receive a PhysicalDownlink Control Channel (PDCCH) and a Physical Downlink Shared Channel(PDSCH) according to information included in the PDCCH so as to acquiremore detailed system information (S302).

Meanwhile, if the eNB is initially accessed or radio resources forsignal transmission are not present, the UE may perform a Random AccessProcedure (RACH) (step S303 to S306) with respect to the eNB. In thiscase, the UE may transmit a specific sequence through a Physical RandomAccess Channel (PRACH) as a preamble (S303 and S305), and receive aresponse message of the preamble through the PDCCH and the PDSCHcorresponding thereto (S304 and S306). In the case of contention-basedRACH, a contention resolution procedure may be further performed.

The UE which performs the above procedures may perform PDCCH/PDSCHreception (S307) and Physical Uplink Shared Channel PUSCH)/PhysicalUplink Control Channel (PUCCH) transmission (S308) as a generaluplink/downlink signal transmission procedure. The control informationtransmitted from the UE to the eNB in uplink or transmitted from the eNBto the UE in downlink includes a downlink/uplink ACK/NACK signal, aChannel Quality Indicator (CQI), a Precoding Matrix Index (PMI), a RankIndicator (RI), and the like. In the case of the 3GPP LTE system, the UEmay transmit the control information such as CQI/PMI/RI through thePUSCH and/or the PUCCH.

FIG. 4 is a diagram showing the structure of a radio frame used in aLong Term Evolution (LTE) system.

Referring to FIG. 4, the radio frame has a length of 10 ms(327200×T_(s)) and includes 10 subframes with the same size. Each of thesubframes has a length of 1 ms and includes two slots. Each of the slotshas a length of 0.5 ms (15360×T_(s)), T_(s) denotes a sampling time, andis represented by T_(s)=1/(15 kHz×2048)=3.2552×10⁻⁸ (about 33 ns). Eachslot includes a plurality of OFDM or SC-FDMA symbols in a time domain,and includes a plurality of resource blocks (RBs) in a frequency domain.In the LTE system, one RB includes 12 subcarriers×7(6) OFDM or SC-FDMAsymbols. A Transmission Time Interval (TTI) which is a unit time fortransmission of data may be determined in units of one or moresubframes. The structure of the radio frame is only exemplary and thenumber of subframes included in the radio frame, the number of slotsincluded in the subframe, or the number of OFDM or SC-FDMA symbolsincluded in the slot may be variously changed.

FIG. 5 is a diagram showing the functional structure of a downlink radioframe in an LTE system.

Referring to FIG. 5, the downlink radio frame includes 10 subframeshaving the same length. In the 3GPP LTE system, a subframe is defined asa basic time unit of packet scheduling in an entire downlink frequency.Each subframe is divided into a region (control region) for transmittingscheduling information and other control channels and a region (dataregion) for transmitting downlink data. The control region starts from afirst OFDM symbol of a subframe and includes one or more OFDM symbols.The size of the control region may be independently set according tosubframe. The control region is used to transmit an L1/L2 (layer 1/layer2). The data region is used to transmit downlink traffic.

FIG. 6 is a diagram showing a control channel included in a controlregion of a subframe in an LTE system.

Referring to FIG. 6, the subframe includes 14 OFDM symbols. The first tothird OFDM symbols are used as a control region and the remaining 13 to11 OFDM symbols are used as a data region, according to subframeconfiguration.

In FIG. 7, R1 to R4 denote reference signals (RS) for antennas 0 to 3.The RS is fixed to a constant pattern within a subframe regardless ofthe control region and the data region. A control channel is allocatedto resources, to which the RS is not allocated, in the control region,and a traffic channel is also allocated to resources, to which the RS isnot allocated, in the control region. Examples of the control channelallocated to the control region include a Physical Control FormatIndicator Channel (PCFICH), a Physical Hybrid-ARQ Indicator Channel(PHICH), a Physical Downlink Control Channel (PDCCH), etc.

The Physical Control Format Indicator Channel (PCFICH) informs the UE ofthe number of OFDM symbols used for the PDCCH per subframe. The PCFICHis located at a first OFDM symbol and is set prior to the PHICH and thePDCCH. The PCFICH includes four Resource Element Groups (REGs) and theREGs are dispersed in the control region based on a cell ID. One REGincludes four resource elements (REs). The PCFICH has a value of 1 to 3and is modulated using a Quadrature Phase Shift Keying (QPSK) scheme.

The Physical Hybrid-ARQ Indicator Channel (PHICH) is used to transmitHARQ ACK/NACK for uplink transmission. The PHICH includes three REGs andis scrambled. on a cell-specific basis. ACK/NACK is indicated by onebit, is spread with a spreading factor (SF) of 2 or 4, and is repeatedthree times. A plurality of PHICHs may be mapped to the same resources.The PHICH is modulated by binary phase shift keying (BPSK).

The Physical Downlink Control Channel (PDCCH) is allocated to the firstn OFDM symbols of a subframe. Here, n is an integer of 1 or more and isindicated by a PCFICH. The PDCCH includes one or more Control ChannelElements (CCEs), which will be described in greater detail below. ThePDCCH informs each UE or a UE group of information associated withresource allocation of a Paging Channel (PCH) and a Downlink-SharedChannel (DL-SCH), both of which are transport channels, uplinkscheduling grant, HARQ information, etc.

The paging channel (PCH) and the downlink-shared channel (DL-SCH) aretransmitted through a PDSCH. Accordingly, the eNB and the UE transmitand receive data through the PDSCH except for specific controlinformation or specific service data.

Information indicating to which UE (one or a plurality of UEs) data ofthe PDSCH is transmitted and information indicating how the UEs receiveand decode the PDSCH data are transmitted in a state of being includedin the PDCCH. For example, it is assumed that a specific PDCCH isCRC-masked with a Radio Network Temporary Identity (RNTI) “A”, andinformation about data transmitted using radio resource (e.g., frequencylocation) “B” and transmission format information (e.g., transmissionblock size, modulation scheme, coding information, or the like) “C” istransmitted via a specific subframe. In this case, one or more UEslocated within a cell monitor a PDCCH using its own RNTI information,and if one or more UEs having “A” RNTI are present, the UEs receive thePDCCH and receive the PDSCH indicated by “B” and “C” through theinformation about the received PDCCH.

FIG. 7 is a diagram showing the structure of an uplink subframe used inan LTE system.

Referring to FIG. 7, an uplink subframe includes a plurality (e.g., two)of slots. The number of SC-FDMA symbols included in the slot may bechanged according to CP length. For example, the slot may include sevenSC-FDMA symbols in a normal CP case. An uplink subframe is divided intoa data region and a control region. The data region includes a PUSCH andis used to transmit a data signal such as voice. The control regionincludes a PUCCH and is used to transmit control information. The PUCCHincludes an RB pair (e.g., m=0, 1, 2. 3) located at both ends of thedata region on a frequency axis and is “frequency-hopped” at a slotedge. The control information includes ACK/NACK, CQI, PMI, RI, etc.

FIG. 8 is another diagram showing the structure of an uplink subframe inan LTE system.

Referring to FIG. 8, a subframe 800 having a length of 1 ms, which is abasic unit of LTE uplink transmission, includes two slots 801 eachhaving a length of 0.5 ms. In case of normal cyclic prefix (CP), eachslot includes seven symbols 802 and one symbol corresponds to oneSC-FDMA symbol. An RB 803 is a resource allocation unit corresponding to12 subcarriers in a frequency domain and one slot in a time domain. Thestructure of the uplink subframe of LTE is roughly divided into a dataregion 804 and a control region 805. The data region refers to a seriesof communication resources used to transmit data such as voice orpackets to each UE and corresponds to resources excluding resourcesbelonging to the control region in a subframe. The control region refersto a series of communication resources used to transmit a downlinkchannel quality report from each UE, reception ACK/NACK for a downlinksignal, an uplink scheduling request, etc.

As shown in FIG. 8, a region 806 for transmitting a sounding referencesignal (SRS) within one subframe is a part including SC-FDMA symbolslocated at the last of a time axis in one subframe and the SRS istransmitted via a data transmission band on a frequency axis. SRSs ofseveral UEs transmitted using the last SC-FDMA symbols of the samesubframe may be distinguished according to frequency location.

The SRS is composed of constant amplitude zero auto correlation (CAZAC)sequences. SRSs transmitted from several UEs are CAZAC sequencesr^(SRS)(n)=r_(u,v) ^((α))(n) having different cyclic shift values aaccording to Equation 1.

$\begin{matrix}{\alpha = {2\pi \; \frac{n_{SRS}^{cs}}{8}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

where, n_(SRS) ^(cs) is a value set to each UE by a higher layer and hasan integer value of 0 to 7. Accordingly, the cyclic shift value may haveeight values according to n_(SRS) ^(cs).

CAZAC sequences generated from one CAZAC sequence through cyclic shifthave a zero correlation value with sequences having different cyclicshift values. Using such property, SRSs of the same frequency domain maybe divided according to CAZAC sequence cyclic shift values. The SRS ofeach UE is allocated to the frequency according to a parameter set bythe eNB. The UE performs frequency hopping of the SRS so as to transmitthe SRS with an overall uplink data transmission bandwidth.

Hereinafter, a detailed method of mapping physical resources fortransmitting SRSs in an LTE system will be described.

In order to satisfy transmit power P_(SRS) of a UE, an SRS sequencer^(SRS)(n) is first multiplied by an amplitude scaling factor β_(SRS)and is then mapped to a resource element (RE) having an index (k, 1)from r^(SRS) (0) by Equation 2.

$\begin{matrix}{a_{{{2k} + k_{0}},l} = \left\{ \begin{matrix}{\beta_{SRS}\; {r^{SRS}(k)}} & {{k = 0},1,\ldots \mspace{14mu},{M_{{sc},b}^{RS} - 1}} \\0 & {otherwise}\end{matrix} \right.} & {{Equation}\mspace{14mu} 2}\end{matrix}$

where, k₀ denotes a frequency domain start point of an SRS and isdefined by Equation 3.

$\begin{matrix}{k_{0} = {k_{0}^{\prime} + {\sum\limits_{b = 0}^{B_{SRS}}{2M_{{sc},b}^{RS}n_{b}}}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

where, n _(b) denotes a frequency location index. k′₀ for a generaluplink subframe is defined by Equation 4 and k′₀ for an uplink pilottime UpPTS is defined by Equation 5.

$\begin{matrix}{\mspace{20mu} {k_{0}^{\prime} = {{\left( {\left\lfloor {N_{RB}^{UL}/2} \right\rfloor - {m_{{SRS},0}/2}} \right)N_{SC}^{RB}} + k_{TC}}}} & {{Equation}\mspace{14mu} 4} \\{k_{0}^{\prime} = \left\{ \begin{matrix}{{\left( {N_{RB}^{UL} - m_{{SRS},0}^{{ma}\; x}} \right)N_{sc}^{RB}} + k_{TC}} & {{{if}\mspace{14mu} \begin{pmatrix}{\left( {n_{f}{mod}\; 2} \right) \times} \\{\left( {2 - N_{SP}} \right) + n_{hf}}\end{pmatrix}{mod}\; 2} = 0} \\k_{TC} & {otherwise}\end{matrix} \right.} & {{Equation}\mspace{14mu} 5}\end{matrix}$

In Equations 4 and 5, k_(TC) denotes a transmissionComb parametersignaled to a UE via a higher layer and has a value of 0 or 1. Inaddition, n_(hf) is 0 in an uplink pilot time slot of a first half frameand is 0 in an uplink pilot slot of a second half frame. M_(sc,b) ^(RS)is the length of the SRS sequence expressed in subcarrier units definedby Equation 6, that is, a bandwidth.

M _(sc,b) ^(RS) =m _(SRS,b) N _(sc) ^(RB)/2   Equation 6

In Equation 6, m_(SRS,b) is a value signaled from an eNB according to anuplink bandwidth N_(RB) ^(UL) as shown in Tables 1 to 4.

In order to acquire m_(SRSb), a cell-specific parameter C_(SRS) havingan integer value of 0 to 7 and a UE-specific parameter B_(SRS) having aninteger value of 0 to 3 are necessary. The values of C_(SRS) and B_(SRS)are provided by a higher layer.

TABLE 1 b_(hop) = 0, 1, 2, 3 and 6 ≦ N_(RB) ^(UL) ≦ 40 SRS SRS- SRS-SRS- SRS- bandwidth Bandwidth Bandwidth Bandwidth Bandwidthconfiguration B_(SRS) = 0 B_(SRS) = 1 B_(SRS) = 2 B_(SRS) = 3 C_(SRS)m_(SRS, b) N_(b) m_(SRS, b) N_(b) m_(SRS, b) N_(b) m_(SRS, b) N_(b) 0 361 12 3 4 3 4 1 1 32 1 16 2 8 2 4 2 2 24 1 4 6 4 1 4 1 3 20 1 4 5 4 1 4 14 16 1 4 4 4 1 4 1 5 12 1 4 3 4 1 4 1 6 8 1 4 2 4 1 4 1 7 4 1 4 1 4 1 41

TABLE 2 b_(hop) = 0, 1, 2, 3 and 40 < N_(RB) ^(UL) ≦ 60 SRS SRS- SRS-SRS- SRS- bandwidth Bandwidth Bandwidth Bandwidth Bandwidthconfiguration B_(SRS) = 0 B_(SRS) = 1 B_(SRS) = 2 B_(SRS) = 3 C_(SRS)m_(SRS, 0) N₀ m_(SRS, 1) N₁ m_(SRS, 2) N₂ m_(SRS, 3) N₃ 0 48 1 24 2 12 24 3 1 48 1 16 3 8 2 4 2 2 40 1 20 2 4 5 4 1 3 36 1 12 3 4 3 4 1 4 32 116 2 8 2 4 2 5 24 1 4 6 4 1 4 1 6 20 1 4 5 4 1 4 1 7 16 1 4 4 4 1 4 1

TABLE 3 b_(hop) = 0, 1, 2, 3 and 60 < N_(RB) ^(UL) ≦ 80 SRS SRS- SRS-SRS- SRS- bandwidth Bandwidth Bandwidth Bandwidth Bandwidthconfiguration B_(SRS) = 0 B_(SRS) = 1 B_(SRS) = 2 B_(SRS) = 3 C_(SRS)m_(SRS, 0) N₀ m_(SRS, 1) N₁ m_(SRS, 2) N₂ m_(SRS, 3) N₃ 0 72 1 24 3 12 24 3 1 64 1 32 2 16 2 4 4 2 60 1 20 3 4 5 4 1 3 48 1 24 2 12 2 4 3 4 48 116 3 8 2 4 2 5 40 1 20 2 4 5 4 1 6 36 1 12 3 4 3 4 1 7 32 1 16 2 8 2 4 2

TABLE 4 b_(hop) = 0, 1, 2, 3 and 80 < N_(RB) ^(UL) ≦ 110 SRS SRS- SRS-SRS- SRS- bandwidth Bandwidth Bandwidth Bandwidth Bandwidthconfiguration B_(SRS) = 0 B_(SRS) = 1 B_(SRS) = 2 B_(SRS) = 3 C_(SRS)m_(SRS, 0) N₀ m_(SRS, 1) N₁ m_(SRS, 2) N₂ m_(SRS, 3) N₃ 0 96 1 48 2 24 24 6 1 96 1 32 3 16 2 4 4 2 80 1 40 2 20 2 4 5 3 72 1 24 3 12 2 4 3 4 641 32 2 16 2 4 4 5 60 1 20 3 4 5 4 1 6 48 1 24 2 12 2 4 3 7 48 1 16 3 8 24 2

As described above, the UE may perform frequency hopping of the SRS soas to transmit the SRS with the overall uplink data transmissionbandwidth. Such frequency hopping is set by a parameter b_(hop) having avalue of 0 to 3 received from a higher layer.

If frequency hopping of the SRS is deactivated, that is ifb_(hop)≧B_(SRS), a frequency location index n_(b) has a constant valueas shown in Equation 7. Here, n_(RRC) is a parameter received from ahigher layer.

n _(b)=└4n _(RRC) /m _(SRS,b)┘mod N _(b)   Equation 7

Meanwhile, if frequency hopping of the SRS is activated, that is,b_(hop)<B_(SRS), a frequency location index n_(b) is defined byEquations 8 and 9.

$\begin{matrix}{n_{b} = \left\{ \begin{matrix}{\left\lfloor {4{n_{RRC}/m_{{SRS},b}}} \right\rfloor {mod}\; N_{b}} & {b \leq b_{hop}} \\{\left\{ {{F_{b}\left( n_{SRS} \right)} + \left\lfloor {4{n_{RRC}/m_{{SRS},b}}} \right\rfloor} \right\} {mod}\; N_{b}} & {otherwise}\end{matrix} \right.} & {{Equation}\mspace{14mu} 8} \\{{F_{b}\left( n_{SRS} \right)} = \left\{ \begin{matrix}\begin{matrix}{{\left( {N_{b}/2} \right)\left\lfloor \frac{n_{SRS}{mod}\; \Pi_{b^{\prime} = b_{hop}}^{b}N_{b^{\prime}}}{\Pi_{b^{\prime} = b_{hop}}^{b - 1}N_{b^{\prime}}} \right\rfloor} +} \\\left\lfloor \frac{n_{SRS}{mod}\; \Pi_{b^{\prime} = b_{hop}}^{b}N_{b^{\prime}}}{2\Pi_{b^{\prime} = b_{hop}}^{b - 1}N_{b^{\prime}}} \right\rfloor\end{matrix} & {{if}\mspace{14mu} N_{b}\mspace{14mu} {even}} \\{\left\lfloor {N_{b}/2} \right\rfloor \left\lfloor {{n_{SRS}/\Pi_{b^{\prime} = b_{hop}}^{b - 1}}N_{b^{\prime}}} \right\rfloor} & {{if}\mspace{14mu} N_{b}\mspace{14mu} {odd}}\end{matrix} \right.} & {{Equation}\mspace{14mu} 9}\end{matrix}$

where, n_(SRS) is a parameter used to calculate the number of times oftransmission of the SRS and is defined by Equation 10.

$\begin{matrix}{n_{SRS} = \left\{ \begin{matrix}\begin{matrix}{{2N_{SP}n_{f}} + {2\left( {N_{SP} - 1} \right)\left\lfloor \frac{n_{s}}{10} \right\rfloor} +} \\{\left\lfloor \frac{T_{offset}}{T_{{offset}\; \_ \; {ma}\; x}} \right\rfloor,}\end{matrix} & \begin{matrix}{{for}\mspace{14mu} 2\mspace{14mu} {ms}\mspace{14mu} {SRS}\mspace{14mu} {periodicity}\mspace{14mu} {of}} \\{{TDD}\mspace{14mu} {frame}\mspace{14mu} {structure}}\end{matrix} \\{\left\lfloor {\left( {{n_{f} \times 10} + \left\lfloor {n_{s}/2} \right\rfloor} \right)/T_{SRS}} \right\rfloor,} & {otherwise}\end{matrix} \right.} & {{Equation}\mspace{14mu} 10}\end{matrix}$

In Equation 10, T_(SRS) denotes the periodicity of an SRS and T_(offset)denotes a subframe offset of an SRS. In addition, n_(s) denotes a slotnumber and n_(f) denotes a frame number.

A UE-specific SRS configuration index I_(SRS) for setting theperiodicity T_(SRS) and the subframe offset T_(offset) of a UE-specificSRS signal is shown in Tables 5 and 6 according to FDD and TDD. Inparticular, Table 5 shows the SRS configuration index for FDD and Table6 shows the SRS configuration index for TDD.

TABLE 5 SRS Configuration SRS Periodicity SRS Subframe Index I_(SRS)T_(SRS) (ms) Offset T_(offset) 0-1 2 I_(SRS) 2-6 5 I_(SRS) − 2   7-16 10I_(SRS) − 7  17-36 20 I_(SRS) − 17 37-76 40 I_(SRS) − 37  77-156 80I_(SRS) − 77 157-316 160  I_(SRS) − 157 317-636 320  I_(SRS) − 317 637-1023 reserved reserved

TABLE 6 Configuration SRS Periodicity SRS Subframe Index I_(SRS) T_(SRS)(ms) Offset T_(offset) 0 2 0, 1 1 2 0, 2 2 2 1, 2 3 2 0, 3 4 2 1, 3 5 20, 4 6 2 1, 4 7 2 2, 3 8 2 2, 4 9 2 3, 4 10-14 5 I_(SRS) − 10 15-24 10I_(SRS) − 15 25-44 20 I_(SRS) − 25 45-84 40 I_(SRS) − 45  85-164 80I_(SRS) − 85 165-324 160  I_(SRS) − 165 325-644 320  I_(SRS) − 325 645-1023 reserved reserved

FIG. 9 is a conceptual diagram illustrating carrier aggregation. Carrieraggregation refers to a method of using a plurality of componentcarriers as a large logical frequency band in order to use a widerfrequency band in a radio communication system.

Referring to FIG. 9, an entire system band (BW) is a logical band havinga maximum bandwidth of 100 MHz. The entire system band includes fivecomponent carriers (CCs) and each CC has a maximum bandwidth of 20 MHz.The CC includes one or more physically contiguous subcarriers. Althoughall CCs have the same bandwidth in FIG. 9, this is only exemplary andthe CCs may have different bandwidths. Although the CCs are shown asbeing contiguous in the frequency domain in FIG. 9, FIG. 9 merely showsthe logical concept and thus the CCs may be physically contiguous orseparated.

Different center frequencies may be used fir the CCs or one commoncenter frequency may be used for physically contiguous CCs. For example,in FIG. 9, if it is assumed that all CCs are physically contiguous, acenter frequency A may be used. If it is assumed that CCs are notphysically contiguous, a center frequency A, a center frequency B andthe like may be used for the respective CCs.

In the present specification, the CC may correspond to a system band ofa legacy system, By defining the CC based on the legacy system, it ispossible to facilitate backward compatibility and system design in aradio communication environment in which an evolved UE and a legacy UEcoexist. For example, if the LTE-A system supports carrier aggregation,each CC may correspond to the system band of the LTE system. In thiscase, the CC may have any one bandwidth such as 1.25, 2.5, 5, 10 or 20MHz.

In the case in which the entire system hand is extended by carrieraggregation, a frequency band used for communication with each UE isdefined in CC units. A UE A may use 100 MHz which is the bandwidth ofthe entire system band and perform communication using all five CCs.Each of UEs B₁ to B₅ may only use a bandwidth of 20 MHz and performcommunication using one CC. Each of UEs C₁ and C₂ may use a bandwidth of40 MHz and perform communication using two CCs. The two CCs may becontiguous or discontiguous. The UE C₁ uses two discontiguous CCs andthe UE C₂ uses two contiguous CCs.

While one downlink component carrier and one uplink component carrierare used in an LTE system, several component carriers may be used in anLTE-A system as shown in FIG. 8. At this time, a method of scheduling adata channel by a control channel may be divided into a linked carrierscheduling scheme and a cross carrier scheduling scheme. Morespecifically, in the linked carrier scheduling scheme, a control channeltransmitted via a specific CC schedules only a data channel via thespecific CC, similarly to the existing LTE system using a single CC. Inthe cross carrier scheduling scheme, a control channel transmitted via aprimary CC using a carrier indicator field (CIF) schedules a datachannel transmitted via the primary CC or another CC.

Hereinafter, an uplink transmission power control (TPC) command of a UEin an LTE system will be described. The TPC command is signaled as anoffset value transmitted from an eNodeB via a PDCCH and uplinktransmission power of the UE is dynamically controlled by the offsetvalue. The UE needs to check the TPC in every subfrarne unlessdiscontinuous reception (DRX) is set. As one method of transmitting theTPC command to the UE, the TPC command is included in an uplink ordownlink grant message (that is, DCI formats 0, 1, 1A, 1B, 1C, 1D, 2 and2A) for the UE. The TPC command included in the uplink grant messagecontrols the transmit power of a PUSCH and the TPC command included inthe downlink grant message controls the transmit power of a PUCCH.

In addition, a method of signaling an aggregation of TPC commands of aplurality of UEs may be taken into account and is supported by an LTEsystem via DCI formats 3 and 3A.

FIG. 10 is a diagram showing the structure of DCI formats 3 and 3A in anLTE system. If a UE supports DCI formats 3 and 3A, the UE decodescontrol information using one of DCI formats 3 and 3A through higherlayer signaling and reads transmit power intimation thereof.

Referring to FIG. 10, DCI format 3 includes transmit power informationhaving a size of 2 bits with respect to each UE and DCI format 3Aincludes transmit power information of 1 bit. Since DCI formats 3 and 3Ahave the same payload size, if the size of DCI format 3 is an odd bit, apadding bit 0 may be inserted in the end thereof. The payload size ofDCI formats 3 and 3A are equal to those of DCI format 0 and 1A, and thusthe number of times of blind decoding may be reduced.

Hereinafter, a dynamic activation/deactivation scheme of a downlinkcomponent carrier according to an embodiment of the present inventionwill be described.

As described above, in an LTE-A system, one UE may use multiplecomponent carriers. A UE is informed of the multiple component carriersusing an RRC configuration signal which is a higher layer signal and theUE may receive downlink data using the multiple component carriers ortransmit uplink data via the multiple of component carriers. However, ifa data traffic property of the UE is not stable, all component carrierssignaled from the higher layer may not be efficiently used.

Accordingly, recently, a method of dynamically activating/deactivating adownlink component carrier set in order to efficiently use componentcarriers and prevent unnecessary power consumption due to buffering hasbeen proposed. As such an activation method, a method ofactivating/deactivating each component carrier or a method ofsimultaneously activating/deactivating all downlink component carriersexcept for a specific component carrier (e.g., a downlink anchorcomponent carrier) may be taken into account.

FIG. 11 is a diagram illustrating a method of schedulingactivation/deactivation of a downlink component carrier according to anembodiment of the present invention.

Referring to FIG. 11, decrease or increase in the number of downlinkcomponent carriers received using an activation/deactivation signalwhich is dynamic signaling in a state in which a UE sets a total of fourdownlink component carriers as downlink component carriers allocatedthereto may be taken into account. Such a dynamicactivation/deactivation signal may be transmitted via a physical layercontrol signal (PDCCH) or a MAC layer signal (PDSCH).

In the above-described dynamic activation/deactivation method of thedownlink component carrier, it is possible to reduce power consumptionof a UE by dynamically controlling downlink component carriers receivedat the UE whenever necessary.

Hereinafter, a dynamic activation/deactivation method of a soundingreference signal according to an embodiment of the present inventionwill be described.

In an LTE-A system, various schemes such as an uplink MIMO transmissionof a UE using a plurality of antennas, a Coordinated Multi-Point (CoMP)scheme for transmitting and receiving a signal cooperatively with aplurality of eNodeBs, a network in which heterogeneous networks arecombined, and an uplink discontinuous data allocation (cluster) schemehave been developed. Accordingly, in order to support such schemes,transmission of a sounding reference signal for uplink channelmeasurement needs to be improved and a method of dynamicallyactivating/deactivating sounding reference signal transmission may betaken into account as a method of improving a sounding reference signaltransmission scheme.

That is, the method of dynamically activating/deactivating the soundingreference signal refers to a method of receiving information about atransmission period, an offset, etc. of a sounding reference signal toprepare sounding reference signal transmission andactivating/deactivating actual sounding reference signal transmissionusing a signal (e.g., a PDCCH which is a physical layer control signalor an MAC layer signal) faster than a higher layer signal.

At this time, a method of activating/deactivating sounding referencesignal transmission on a per uplink component carrier basis may be takeninto account and a method of simultaneously activating/deactivatingsounding reference signal transmission of all uplink component carriersexcept for a specific component carrier (e.g., an uplink anchorcomponent carrier) may be taken into account.

FIG. 12 is a diagram illustrating a method of schedulingactivation/deactivation of sounding reference signal transmission of anuplink component carrier according to an embodiment of the presentinvention.

Referring to FIG. 12, sounding reference signal transmission of alluplink component carriers except for a first uplink component isdeactivated when a first dynamic sounding reference signal transmissionactivation/deactivation signal is applied while a sounding referencesignal is transmitted using four uplink component carriers, soundingreference signal transmission is deactivated in first and fourth uplinkcomponent carriers when a second dynamic sounding reference signaltransmission activation/deactivation signal is applied, and soundingreference signal transmission is activated in second and third uplinkcomponent carriers,

Similarly, sounding reference signal transmission in the first uplinkcomponent carrier is deactivated after a third dynamic soundingreference signal transmission activation/deactivation signal is applied,and sounding reference signal transmission is activated in the remaininguplink component carriers.

The method of dynamically signaling activation/deactivation of soundingreference signal transmission in each uplink component carrier may beintroduced in order to perform Time Division Multiplexing (TDM) withrespect to insufficient sounding reference signal transmission resourcesbetween different UEs or to reduce UE power used to transmit anunnecessary sounding reference signal.

However, the method of dynamically signaling activation/deactivation ofsounding reference signal transmission may be extended and used as amethod of controlling an uplink component carrier set used to transmituplink data. That is, while sounding reference signal transmission of aspecific uplink component carrier is deactivated, it is difficult toperform channel estimation of an uplink component carrier at an eNodeBand to send uplink transmission grant using the uplink componentcarrier.

Accordingly, since the activation/deactivation signal of soundingreference signal transmission is similar to the dynamicactivation/deactivation signal of the downlink component carrier interms of use, the present invention proposes a method of simultaneouslytransmitting the activation/deactivation signal of the downlinkcomponent carrier and the activation/deactivation signal of soundingreference signal transmission via one signal as follows.

First, there is a method of using a UE-specific PDCCH or a PDSCH whichis an MAC layer signal. This is a method of sending two kinds ofactivation/deactivation signals to UEs using a UE-specific PDCCH or aPDSCH which is an MAC layer signal. In this case, a method ofsimultaneously transmitting an activation/deactivation signal (e.g.,bitmap information per downlink component carrier) of each downlinkcomponent carrier for all downlink component carriers and a soundingreference signal transmission activation/deactivation signal per uplinkcomponent carrier (e.g., bitmap information per uplink componentcarrier) or simultaneously transmitting two kinds of signals (anactivation/deactivation signal of a downlink component carrier or asounding reference signal transmission activation/deactivation signal ofan uplink component carrier) for commonly activating/deactivating theremaining component carriers except for a specific component carrier(that is, an anchor component carrier) may be taken into account. Inaddition, a method of simultaneously sending signals for commonlyactivating/deactivating a predetermined number of grouped componentscarriers may be taken into account.

There is a method of using a PDCCH for a UE group, similarly to DCIformats 3 and 3A used to control the transmit power of a specific UEgroup in an LTE system, which will be described in greater detail withreference to the drawings.

FIG. 13 is a diagram illustrating a method of simultaneously schedulingactivation/deactivation of a downlink component carrier andactivation/deactivation of sounding reference signal transmission of anuplink component carrier according to an embodiment of the presentinvention.

If each UE controls activation/deactivation of a downlink componentcarrier and activation/deactivation of sounding reference signaltransmission of an uplink component carrier using a signal having a sizeof 1 bit for commonly activating/deactivating CCs except for a specificCC, a DCI format similar to DCI formats 3 and 3A may be designed asshown in FIG. 13. More specifically, as shown in FIG. 13A, a method ofallocating two continuous bits (DL CC activation/deactivation and UL SRSactivation/deactivation) in DCI format 3 to each UE and informing the UEof the location of information to be read using a TPC index (higherlayer signaling) may be taken into account. Similarly to DCI format 3A,a method of individually signaling 1 bit without continuously arrangingsignals of 2 bits as shown in FIG. 13B may be taken into account.

In addition, if an activation/deactivation signal is sent on a percomponent carrier or component carrier group basis, a method of freelyallocating an activation/deactivation signal per component carrier orcomponent carrier group to a specific bit and signaling an index thereofthrough higher layer signaling as shown in FIG. 13B may be taken intoaccount.

In addition, a method of changing RNTI masking in order to distinguishbetween component carriers or component carrier groups may be taken intoaccount. In this case, a method of combining an index of a specific bitand RNTI and simultaneously transmitting activation/deactivation signalsin component carrier units or component carrier group units may be takeninto account.

Hereinafter, a PUSCH extension method in a subframe, in which a soundingreference signal is not transmitted, according to an embodiment of thepresent invention will be described.

In an LTE system, if all UEs perform PUSCH transmission in a subframe inwhich a sounding reference signal is transmitted, data may be set not tobe transmitted in a last SC-FDMA symbol. That is, since the last symbolis used to transmit a sounding reference signal, all UEs may not use thelast SC-FDMA symbol in a subframe in which a sounding reference signalis transmitted, that is, uplink data (PUSCH) may be set to betransmitted using only 11 SC-FDMA symbols, in order to preventinterference between a sounding reference signal symbol and an uplinkdata symbol of a UE.

However, since sounding reference signal symbols may not be used over anoverall bandwidth, a method of performing PUSCH transmission in a statein which a last SC-FDMA symbol is always empty may cause inefficientresource use. Accordingly, information indicating whether PUSCHtransmission is performed even using the last SC-FDMA symbol istransmitted in uplink grant indicating PUSCH transmission such thatresources are efficiently used in a subframe in which a soundingreference signal is transmitted. That is, if an actual soundingreference signal is not transmitted in a bandwidth allocated fortransmitting a PUSCH in a specific subframe in which a soundingreference signal may be transmitted, the PUSCH may be transmitted evenusing the last SC-FDMA symbols by providing PUSCH extension informationin uplink grant.

Further, the case of performing dynamic scheduling so as to transmit anaperiodic sounding reference signal to a specific UE using specificfrequency resources in a subframe in which a sounding reference signalis not transmitted may be taken into account. Even in this case, as inan LTF system, if uplink data (PUSCH) is transmitted without using alast SC-FDMA symbol, the last SC-FDMA symbol may not be efficientlyused. Accordingly, PUSCH extension information is transmitted in uplinkgrant and thus an operation in which a dynamically triggered aperiodicsounding reference signal and a PUSCH do not collide with each other ispossible even in a subframe in which a sounding reference signal is nottransmitted.

In addition, the case of allocating a plurality of uplink componentcarriers to the UE and signaling only sounding reference signaltransmission in an entire frequency band or some frequency bands of aspecific uplink component carrier may be taken into account. Even inthis case, if uplink data (PUSCH) is transmitted without using a lastSC-FDMA symbol, the last SC-FDMA symbol of every uplink componentcarrier may not be efficiently used. Similarly, PUSCH extensioninformation of an uplink component carrier in which a sounding referencesignal is not transmitted is transmitted in uplink grant and uplink datais transmitted using a last SC-FDMA symbol in a subframe in which asounding reference signal is not transmitted, thereby efficiently usingresources.

In addition, a multi-cell cooperative system, for example, in a systemin which a femto cell is located in a macro cell and a first UEcommunicates with both the macro cell and the fimito cell, theabove-described scheme may be used even upon sounding reference signaltransmission of a second UE and PUSCH transmission of a first UE. Here,it is assumed that the PUSCH is transmitted even in the last symbol.That is, since the PUSCH transmitted by the first UE may causeinterference in reception of a sounding reference signal in the macrocell, a last symbol may not be allocated to the PUSCH transmitted by thefirst UE.

As a method of transmitting PUSCH extension information in uplink grant,a method of explicitly adding 1-bit information to uplink grant may betaken into account or a method of implicitly using CRC masking or ascrambling sequence may be taken into account. In addition, a signalingmethod using a specific state combination of bits used in uplink grantmay also be taken into account.

FIG. 14 is a block diagram showing a communication apparatus accordingto an embodiment of the present invention.

Referring to FIG. 14, a communication apparatus 1400 includes aprocessor 1410, a memory 1420, a Radio Frequency (RF) module 1430, adisplay module 1440 and a user interface module 1450.

The communication apparatus 1400 is shown for convenience of descriptionand some modules thereof may be omitted. In addition, the communicationapparatus 1400 may further include necessary modules. In addition, somemodules of the communication apparatus 1400 may be subdivided. Theprocessor 1410 is configured to perform an operation of the embodimentof the present invention described with reference to the drawings.

More specifically, if the communication apparatus 1400 is included inthe eNB, the processor 1410 serve to generate and map a control signalto a control channel set in a plurality of frequency blocks. If thecommunication apparatus 1400 is included in the UE, the processor 1410may check a control channel allocated thereto from a signal receivedfrom a plurality of frequency blocks and extract a control signaltherefrom.

Thereafter, the processor 1410 may perform a necessary operation basedon the control signal. For a detailed description of the processor 1410,reference may be made to the description associated with FIGS. 1 to 13.

The memory 1420 is connected to the processor 1410 so as to store anoperating system, an application, program code, data and the like. TheRF module 1430 is connected to the processor 1410 so as to perform afunction for converting a baseband signal into a radio signal orconverting a radio signal into a baseband signal. The RF module 1430performs analog conversion, amplification, filtering and frequencyup-conversion or inverse processes thereof. The display module 1440 isconnected to the processor 1410 so as to display a variety ofinformation. As the display module 1440, although not limited thereto, awell-known device such as a Liquid Crystal Display (LCD), a LightEmitting Diode (LED), or an Organic Light Emitting Diode (OLED) may beused. The user interface module 1450 is connected to the processor 1410and may be configured by a combination of well-known user interfacessuch as a keypad and a touch screen.

The above-described embodiments are proposed by combining constituentcomponents and characteristics of the present invention according to apredetermined format. The individual constituent components orcharacteristics should be considered to be optional factors on thecondition that there is no additional remark. If required, theindividual constituent components or characteristics may not be combinedwith other components or characteristics. Also, some constituentcomponents and/or characteristics may be combined to implement theembodiments of the present invention. The order of operations to bedisclosed in the embodiments of the present invention may be changed toanother. Some components or characteristics of any embodiment may alsobe included in other embodiments, or may be replaced with those of theother embodiments as necessary. Moreover, it will be apparent that someclaims referring to specific claims may be combined with another claimsreferring to the other claims other than the specific claims toconstitute the embodiment or add new claims by means of amendment afterthe application is filed.

The above-mentioned embodiments of the present invention are disclosedon the basis of a data communication relationship between a base stationand an RN. Specific operations to be conducted by the base station inthe present invention may also be conducted by an upper node of the basestation as necessary, in other words, it will be obvious to thoseskilled in the art that various operations for enabling the base stationto communicate with the UE in a network composed of several networknodes including the base station will be conducted by the base stationor other network nodes other than the base station. The term “BaseStation” may be replaced with the terms fixed station, Node-B, eNode-B(eNB), or access point as necessary.

The embodiments of the present invention can be implemented by a varietyof means, for example, hardware, firmware, software, or a combinationthereof. In the case of implementing the present invention by hardware,the present invention can be implemented through application specificintegrated circuits (ASICs), Digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), a processor, a controller, amicrocontroller, a microprocessor, etc.

If operations or functions of the present invention are implemented byfirmware or software, the present invention can be implemented in theform of a variety of formats, for example, modules, procedures,functions, etc. The software codes may be stored in a memory unit so asto be driven by a processor. The memory unit may be located inside oroutside of the processor, so that it can communicate with theaforementioned processor via a variety of well-known parts.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

The present invention is applicable to a wireless communication system.More particularly, the present invention is applicable to a method andapparatus for transmitting an uplink signal at a user equipment (UE) ina wireless communication system.

What is claimed is:
 1. A method of transmitting a sounding referencesignal (SRS) by a user equipment in a wireless communication system, themethod comprising: receiving, from a base station, a physical downlinkcontrol channel (PDCCH) including a carrier indicator field (CIF) and anSRS field via a first component carrier (CC) among a plurality of CCsincluding the first CC and one or more second CCs, the CIF indicating aspecific CC of the one or more second CCs and the SRS field indicatingwhether the user equipment has to transmit the SRS via the specific CCindicated by the CIF; transmitting, to the base station, the SRS on anuplink subframe via the specific CC indicated by the CIF based on SRSconfiguration information if the SRS field is enabled; and receiving,from the base station, a first medium access control (MAC) informationfor deactivating the one or more second CCs other than the first CC, thefirst MAC information including a bitmap for indicating whether the oneor more second CCs are to be deactivated, wherein if a bit for thespecific CC in the bitmap has been disabled, the specific CC and SRStransmission on the specific CC are deactivated.
 2. The method of claim1, further comprising: receiving, from the base station, a radioresource control (RRC) message including the SRS configurationinformation for the user equipment.
 3. The method of claim 1, whereinthe SRS configuration information includes at least one of an SRSbandwidth parameter indicating a SRS transmission bandwidth, an SRSconfiguration index parameter indicating a periodicity and a subframeoffset, a cyclic shift parameter used for performing cyclic shift of theSRS, and a transmission comb parameter indicating a transmission comboffset.
 4. The method of claim 1, further comprising: receiving, fromthe base station, a radio resource control (RRC) message for configuringthe one or more second CCs in addition to the first CC; and receiving,from the base station, a second MAC information for activating the oneor more second CCs other than the first CC.
 5. The method of claim 1,wherein the SRS is an aperiodic type and the SRS field of the PDCCHtriggers the aperiodic type of SRS transmission.
 6. The method of claim1, wherein the SRS is generated and mapped on a last symbol of theuplink subframe,
 7. The method of claim 1, wherein the first CC isalways activated and the one or more second CCs are able to bedeactivated for managing power consumption of the user equipment.
 8. Themethod of claim 1, wherein the first MAC information is received via aphysical downlink shared channel (PDSCH),
 9. A non-transitory computerreadable medium on which a program for executing the method of claim 1is recorded.
 10. A user equipment for transmitting a sounding referencesignal (SRS) in a wireless communication system, the user equipmentcomprising: a receiver configured to receive, from a base station, aphysical downlink control channel (PDCCH) including a carrier indicatorfield (CIF) and an SRS field via a first component carrier (CC) among aplurality of CCs including the first CC and one or more second CCs, theCIF indicating a specific CC of the one or more second CCs and the SRSfield indicating whether the user equipment has to transmit the SRS viathe specific CC indicated by the CIF; a transmitter configured totransmit, to the base station, the SRS on an uplink subframe via thespecific CC indicated by the CIF based on SRS configuration informationif the SRS field is enabled; and a processor configured to control thetransmitter and the receiver, wherein the receiver receives, from thebase station, a first medium access control (MAC) information fordeactivating the one or more second CCs other than the first CC, and thefirst MAC information includes a bitmap for indicating whether the oneor more second CCs are to be deactivated, and wherein if a bit for thespecific CC in the bitmap has been disabled, the specific CC and SRStransmission on the specific CC are deactivated.
 11. The user equipmentof claim 10, wherein the receiver receives, from the base station, aradio resource control (RRC) message including the SRS configurationinformation for the user equipment.
 12. The user equipment of claim 10,wherein the SRS configuration information includes at least one of: anSRS bandwidth parameter indicating a SRS transmission bandwidth, an SRSconfiguration index parameter indicating a periodicity and a subframeoffset, a cyclic shift parameter used for performing cyclic shift of theSRS, and a transmission comb parameter indicating a transmission comboffset.
 13. The user equipment of claim 10, wherein the receiverreceives, from the base station, a radio resource control (RRC) messagefor configuring the one or more second CCs in addition to the first CCand a second MAC information for activating the one or more second CCsother than the first CC.
 14. The user equipment of claim 10, wherein theSRS is an aperiodic type and the SRS field of the PDCCH triggers theaperiodic type of SRS transmission.
 15. The user equipment of claim 10,wherein the SRS is generated and mapped on a last symbol of the uplinksubframe.
 16. The user equipment of claim 10, wherein the first CC isalways activated and the one or more second CCs are able to bedeactivated for managing power consumption of the user equipment. 17.The user equipment of claim 10, wherein the first MAC information isreceived via a physical downlink shared channel (PDSCH).